Agricultural-chemical emulsions produced by dissolving the active ingredients of agricultural chemicals in an organic solvent and adding appropriate emulsifiers thereto are easy to produce and for this reason, numerous products thereof are distributed as typical dosage forms of agricultural-chemical formulation.
In order to achieve emulsifiers excellent in emulsifiability and emulsification stability, there is a need to consider the balance among surfactants' chemical structures, lipophilicity, and hydrophilicity when selecting a surfactant to be used. In general, it is often the case where anionic surfactants and nonionic surfactants are mixed and used in order to achieve favorable emulsifiability in a wide range of water hardnesses and water temperatures.
Examples of nonionic surfactants which are widely used in particular include polyoxyethylene alkylphenyl ethers. In addition, examples of anionic surfactants include the calcium salt of alkylbenzenesulfonate and they adjust the emulsifiability of the matter to be the target of emulsification by mixing with nonionic surfactants.
On the other hand, there are some active ingredients of agricultural chemicals where stability thereof is impaired by emulsifiers. Specifically, decomposition of the active ingredients of cyclohexanedione-based agricultural-chemical/herbicidal emulsions represented by sethoxydim accelerates during preservation due to the influence by moisture or emulsifiers and thus, strict water management or appropriate selection of surfactants is important in agricultural-chemical formulation containing these as active ingredients. For example, in the formulations containing the calcium salts of alkylbenzenesulfonate, since the decomposition of cyclohexanedione-based agricultural-chemical active ingredients tend to accelerate during preservation, there is a need to use other anionic surfactants such as dialkylsulfosuccinates or to reduce the usage of the calcium salts of alkylbenzenesulfonates considerably by increasing the amount of nonionic surfactants or the like. Although polyoxyethylene alkylphenyl ethers, which are excellent in emulsifiability and emulsification stability, have been considered useful as nonionic surfactants to be used concomitantly, it is not necessarily possible to regard them as formulations with sufficient elusifiability or satisfactory emulsification stability. Furthermore, although polyoxyethylene alkylphenyl ethers are surfactants excellent in compatibility, emulsifiability, or the like, there is a possibility of the intermediates thereof, which occur during the decomposition process in the environment, having estrogenic effects (the problem known as environmental hormones) and thus, the idea that mixing them in agricultural chemical formulations is not desirable has been spreading in recent years. For this reason, it is desirable to avoid the use thereof as much as possible since there is a movement to ban the use thereof in agricultural-chemical formulations overseas and also domestically, there is a possibility that the use thereof will be banned or will be restricted in the future. However, when the use of polyoxyethylene alkylphenyl ethers, which are excellent in emulsifiability, is withheld and they are replaced by other nonionic surfactants, preparation of agricultural-chemical emulsions excellent in emusifiability and emulsification stability has been considered a highly difficult problem (for example, refer to non-patent document 1).
Moreover, although the formulations where an alkylbenzenesulfonate amine salt as a synergist is mixed with a termicide for soil treatment are disclosed, the use thereof is not one as an emulsifier and not one which leads to the present invention, which are agricultural-chemical emulsions using alkylbenzenesulfonate amine salts in emulsifiers and having favorable stability and emulsifiability of active ingredients (for example, refer to patent document 1).
[Patent Document 1]
Japanese Laid-Open Patent Application No. 2000-247816
[Non-Patent Document 1]
M. R. Porter, Recent Developments in the Technology of Surfactants (Critical Reports on Applied Chemistry Volume 30), SCI, 1990, p. 9.